Why did Axum want access to both the Nile River and the Red Sea?

Aksum's access to both the Red Sea and the Upper Nile enabled its strong navy to profit in trade between various African (Nubia), Arabian (Yemen), and Indian states. They traded with Roman traders as well as with Egyptian and Persian merchants. The empire was also rich with gold and iron deposits.

Explanation:

sonar maybe? ? i dont know the choices

offline recommendation systems option b

because recommendation systems produce a list of two ways

1. through collaborative filtering

or

2. through content-based filtering